The role of predation by large carnivores in suppressing prey populations and structuring ecosystems is highly debated, calling for a detailed understanding of carnivore diets. Wolves (Canis lupus) roam across three continents and persist throughout widely different ecosystems. Their diet is flexible and may vary spatially as well as seasonally, which requires analysis of diet on different spatial and temporal scales. Few studies have investigated the summer diet of wolves, which is more variable, consists of smaller prey, and requires different methods than studying their winter diet. To better understand the summer diet of wolves, we combined three independently collected wolf scat data sets from three distinctly different portions of the Greater Yellowstone Ecosystem: Yellowstone National Park (2009), Grand Teton National Park (2003 – 2009), and the Absaroka-Beartooth Wilderness (2009 – 2010). These areas represent different ecological conditions and management regimes, which may impact wolf diet. We estimated relative biomass and compared occurrence of different prey species among packs, years, as well as the three regions. In total, we analyzed 1,906 wolf scats and found that neonate cervids, adult elk, and adult deer were the most important prey species in the summer diet of the wolves. We found dietary variation among packs residing in the same area, as well as across years. The occurrence of neonate cervids displayed the most variation, and low occurrence of this prey type often was associated with a more diverse diet. Wolf packs within the national parks had a higher occurrence of medium-sized prey (~ 50 – 70 kg) and lower occurrence of small-sized prey (≤ 20 kg) compared to wolves in the Absaroka-Beartooth Wilderness. These results demonstrate flexibility in summer diet across packs, years, and between regions within the Greater Yellowstone Ecosystem.

中文翻译：

---

大黄石生态系统灰狼 (Canis lupus) 夏季饮食的时空变化

大型食肉动物捕食在抑制猎物种群和构建生态系统方面的作用备受争议，需要对食肉动物的饮食进行详细了解。狼（Canis lupus）在三大洲漫游，并在广泛不同的生态系统中持续存在。他们的饮食是灵活的，可能在空间和季节上有所不同，这需要在不同的空间和时间尺度上分析饮食。很少有研究调查狼的夏季饮食，狼的夏季饮食变化更大，猎物较小，并且需要与研究冬季饮食不同的方法。为了更好地了解狼的夏季饮食，我们结合了来自大黄石生态系统三个明显不同部分的三个独立收集的狼粪便数据集：黄石国家公园 (2009)、大提顿国家公园 (2003 – 2009)、和 Absaroka-Beartooth 荒野 (2009 – 2010)。这些区域代表不同的生态条件和管理制度，可能会影响狼的饮食。我们估计了相对生物量，并比较了包、年份以及三个区域之间不同猎物物种的发生率。我们总共分析了 1,906 只狼的粪便，发现新生鹿科动物、成年麋鹿和成年鹿是狼群夏季饮食中最重要的猎物。我们发现居住在同一地区以及不同年份的人群之间的饮食差异。新生鹿科动物的出现表现出最大的变化，这种猎物类型的低出现率通常与更多样化的饮食有关。与 Absaroka-Beartooth 荒野中的狼相比，国家公园内的狼群中型猎物（~ 50 – 70 公斤）的出现率较高，小型猎物的出现率（≤ 20 公斤）较低。这些结果证明了大黄石生态系统内跨包、跨年和跨区域的夏季饮食的灵活性。